Sequence of pickling, passivation, and hydrostatic testing
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Is there a specific order for pickling, passivation, and hydrostatic testing? Which one should be carried out first?
Personally, I believe acid cleaning and passivation should be carried out after the hydrostatic test, as acid cleaning and passivation are equivalent to rust removal painting and applying a protective coating.
A successful hydrostatic test indicates that the equipment has been manufactured properly, after which pickling and passivation treatment are carried out.
Generally, pickling and passivation are carried out after the pressure test, but when it is not convenient to do so due to structural reasons, it can also be performed during the manufacturing process. Moreover, the smell from acid washing and passivation is rather irritating, and it is mainly carried out inside the equipment; sometimes we also have workers carry out these tasks at appropriate times to protect them. After all, we live in an era that emphasizes putting people first.
Our factory proceeds with pickling only after the water pressure meets the required standards
Personal opinion: Perform acid washing and passivation inside the equipment before pressure testing (acid washing on the outside of the equipment is sufficient for aesthetic reasons); there’s no need to open the manholes after the pressure testing.
Under normal circumstances, a hydrostatic test should be carried out first, followed by pickling and passivation. Because if the hydrostatic test fails, it has to be repaired again.
First conduct a pressure test, then carry out pickling and passivation, as the pressure test is an inspection step; pickling and passivation can only be carried out after the equipment is found to be qualified
Well said; pickling and passivation should be carried out after the pressure test.
The conventional approach is to first use water pressure followed by acid cleaning, but there are exceptions; for instance, when the internal structure makes cleaning difficult, as mentioned by a colleague above, we usually carry out acid cleaning and passivation before welding, and then use a wire brush to treat the welds after welding.
Aren’t acid washing and passivation equipment generally made of stainless steel? Stainless steel equipment is generally subjected to pressure testing, as stainless steel has high requirements regarding water quality. Additionally, overall acid washing and passivation are generally carried out near the end of equipment installation, once all aspects of the equipment have met the required standards; this way, no major modifications to the equipment are made, which would prevent further contamination of it. So generally, pickling and passivation are carried out after the pressure test, followed by a gas tightness test (if necessary).
In our factory, after the hydraulic test is successful, water is drained to dry out the inner walls, and then pickling is carried out
After the hydrostatic test, internal acid cleaning and passivation are carried out; the manhole must be opened, but the sealing performance between the manhole flange and the flange cover cannot be guaranteed
Machining factory: Perform a pressure test first, followed by pickling. In cases where cleaning is particularly difficult as an exception, pickling and passivation can be carried out before welding; after welding, the welds can be treated with a wire brush.
Machining factory: Perform a pressure test first, followed by pickling. In cases where cleaning is particularly difficult as an exception, pickling and passivation can be carried out before welding; after welding, the welds can be treated with a wire brush.
Generally, a hydraulic test is conducted first, and after it passes, pickling and passivation are carried out. If, due to structural reasons, it is not possible to carry out internal acid washing and passivation after the container has been welded together as a whole, it is possible to consider carrying out acid washing and passivation in sections first, and then welding them together later
It is necessary to carry out pickling and passivation first, followed by a pressure test. If the pressure test is successful, the equipment is already in its final form and it becomes difficult to perform pickling at that point. Moreover, pickling and passivation can be carried out throughout the equipment manufacturing process, which also makes it easier for the personnel responsible for these tasks to carry out their work.